Lucent articular lesion in the lateral femoral condyle: source of patellar femoral pain in the athletic adolescent.

A lucent femoral lesion was identified on the articular surface of the lateral femoral condyle in four young athletic males. The lesion occurred on the anterior aspect of the lateral femoral condyle just distal to the epiphyseal plate corresponding to the level of the patella. These patients had patellar femoral pain and symptoms consistent with "chondromalacia patellae" or one of the patellar pain syndromes. This femoral lesion has clinical and radiographic manifestations and probably a traumatic etiology similar to osteochondritis dissecans. Radiographically, the femoral lesion is not demonstrated on the routine anteroposterior, tunnel, or skyline views, and it is easily overlooked on the lateral view. The lesion can be identified radiographically on a Merchant view or on fluoroscopic spot films, and it is "hot" on a radionuclide bone scan. Once identified, arthrography and arthrotomography are useful to determine the integrity of the overlying articular cartilage.